Method for treating acne

ABSTRACT

A method for treatment and modification of material including biological material using an electromagnetic energy source directed to apply the energy to a region of the material, so as to modify and treat a portion of the material in the region. Preferably, an interaction-modifying substance is in the treated region prior to the interaction.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This is a continuation of patent application Ser. No. 09/549,217,entitled “A Method for Treating Acne” filed Apr. 13, 2001 which claimspriority from U.S. provisional patent application No. 60/129,136,entitled, “A Method for Treating and Preventing Acne and Method forPreserving Skin Elasticity” filed Apr. 13, 1999, both of which areassigned to the assignee of the present patent application and areincorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates generally to the application ofenergy to biological tissue, and specifically to the application ofelectromagnetic energy to the skin.

BACKGROUND OF THE INVENTION

[0003] It is known in the art to apply electromagnetic energy tobiological tissue to engender changes therein. Sunbathers, for example,regularly expose themselves to bright sunlight in order to increasemelanocyte activity in the basal layer of the epidermis, responsive tothe sun's ultraviolet (UV) radiation. Artificial UV sources have beencreated to satisfy the desire for a “healthy”-looking tan in the winter.Other forms of electromagnetic energy, laser-light in particular, arecurrently used in a large range of therapeutic and cosmetic procedures,including eye surgery, hair removal, wrinkle removal, and tattooremoval.

[0004] PCT publication WO 98/55035, which is incorporated herein byreference, describes methods for minimizing injury to biological tissuesurrounding a site exposed to pulses of electromagnetic energy.

[0005] U.S. Pat. No. 5,720,894 to Neev et al., which is incorporatedherein by reference, describes biological tissue processing usingUltrashort Pulse High Repetition Rate Laser System for Biological TissueProcessing.

OBJECTS AND SUMMARY OF THE INVENTION

[0006] It is an object of some aspects of the present invention toprovide improved apparatus and methods for applying energy to amaterial.

[0007] It is another object of some aspects of the present invention toprovide improved apparatus and methods for removing heat generatedduring application of electromagnetic energy to a material.

[0008] It is a further object of some aspects of the present inventionto provide improved apparatus and methods for removing heat generatedduring application of electromagnetic energy to biological tissue.

[0009] It is still a further object of some aspects of the presentinvention to provide improved apparatus and methods for decreasing painduring application of electromagnetic energy to biological tissue.

[0010] It is yet a further object of some aspects of the presentinvention to provide improved apparatus and methods for performingmedical treatments.

[0011] It is also an object of some aspects of the present invention toprovide improved apparatus and methods for performing cosmetictreatments.

[0012] It is further an object of some aspects of the present inventionto provide improved apparatus and methods for enabling a visiblewavelength electromagnetic energy source to perform material and tissueremoval and modification.

[0013] It is yet a further object of some aspects of the presentinvention to provide methods and apparatus for enabling a visiblewavelength electromagnetic energy source to perform material and tissueand modification.

[0014] It is also an object of some aspects of the present invention toprovide improved methods and apparatus for enabling a low-powerelectromagnetic energy source to perform tissue removal andmodification, substantially without pain, while controlling the amountof damage or modification to remaining tissue.

[0015] It is also an object of some aspects of the present invention toprovide improved methods and apparatus for enabling a low-powerelectromagnetic energy source to remove unwanted hair, substantiallywithout pain, while controlling the amount of damage to remainingtissue.

[0016] It is also an object of some aspects of the present invention toprovide improved methods and apparatus for enabling a low-powerelectromagnetic energy source to perform tissue treatment that preventthe occurrence of acne.

[0017] It is also an object of some aspects of the present invention toprovide improved methods and apparatus for enabling a low-powerelectromagnetic energy source to perform tissue treatment that curesacne and relieves symptoms of acne.

[0018] In preferred embodiments of the present invention, the tissue ofthe subject has been treated with high absorbance substance so thatsubstantially only the hair follicle openings retain the absorbingparticles. An energy source applies electromagnetic energy to skintissue of a subject preferably so as to cause an expansion and clearingof the follicle duct opening. The expanding opening thus allows clearingremoval of debris and undesired substances within the hair follicles.Tissue mechanical compression is also preferably applied simultaneous orimmediately following the heating and follicular ducts opening action inorder to enhance removal of unwanted substance from the hair follicles.Excess heat may be removed by applying a coolant or a cooling element tothe tissue. Removal of the heat immediately following the application ofthe energy generally reduces the subject's sensation of the heat, and,in particular, reduces any sensation of pain. Moreover, heat removaltypically reduces or eliminates collateral injury to tissue surroundingthe ablated area. Typically, although not necessarily, the tissuecomprises the subject's skin.

[0019] The tissue of the subject may also be treated by applying areflecting coating material to the skin area being treated and thenremoving portions of the reflective coating material proximate a blockedhair follicle, for example, and then applying electromagnetic energy tothe skin area being treated. The electromagnetic energy is substantiallyreflected by the reflective coating so as to protect tissue. Where thereflective coating has been removed, the electromagnetic radiationpropagates through the tissue so as to mitigate the blockage of a hairfollicle.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a simplified pictorial illustration of apparatus fortreating skin in order to prevent and cure acne in accordance with apreferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0021] In preferred embodiments of the present invention, the hair ductsare forced to open so that access oil and unwanted deposition can beremoved from the hair duct.

[0022] To accomplish this, a substance, which can absorb light orelectromagnetic energy, is forced into the ducts. The light orelectromagnetic energy impinging on the target is thus converted intoheat. The heated substance than expand under the influence of thethermal energy, thus forcing the pores to expand and open and allowcleaning and drainage of unwanted substance within the hair duct.

[0023] The expansion process described above, may include any or all ofthe following:

[0024] Volumetric thermal expansion which is proportional to theinserted/absorbing substance temperature, vaporization, sublimation,rapid vaporization, explosive vaporization, expansion due to plasmaformation, expansion due to gas generation, and ablation.

[0025] The high absorbing substance may also become liquefied at somepoint following the start of the heating and expansion event, thusenabling drainage and cleaning of the hair duct including the substanceof high absorption coefficient or high expansion coefficient itself.

[0026] The sequence for the procedure may be as follows:

[0027] A) Apply a substance of high absorption to the skin and forcesaid substance down the hair follicle. Wipe off excess substance onsurface. Irradiate with pulse duration such that no significant heat istransfer to adjacent tissue and ablative interaction occurs at follicleopenings.

[0028] B) Applying a substance of high absorption to the skin and forcesaid substance down the hair follicle. Wipe off excess substance onsurface. Irradiate with a pulse duration such that no heat istransferred to adjacent tissue and rapid heating and expansioninteraction occurs at follicle openings. Pulse duration can be, forexample in the range of about one microsecond and as long as about 100ms, since at these pulse duration ranges thermal diffusion is from about1 μm and up to about a few hundred micrometers. Preferred irradiationtimes are from about 100 microsecond to about 10 millisecond. Suchthermal diffusions are acceptable while significant physical expansionof the absorbing substance can be achieved.

[0029] C) Alternatively, in another embodiment of the present invention,apply a substance of high absorption to the skin and force saidsubstance down the hair follicle. Wipe off excess substance on surface.Irradiate with pulse duration such that no heat is transferred toadjacent tissue and rapid heating, expansion and melting of “absorbingplug” occurs at follicle openings.

[0030] D) Alternatively, in another embodiment of the present invention,apply a substance of high reflection to the surface of the skin. Forcethat substance down the hair ducts while ensuring that the particles insaid substance are such that they are not capable of penetrating(meaning that they are too large) into any other type of skin poresother than the hair follicle (such as surface sweat pores).

[0031] In an alternative, yet embodiment of the present invention, asubstance of high absorption is applied to the surface and is forceddown the hair ducts. The particles in said substance are such that theyare not capable of penetrating into any other pores on the skin surface.The surface is then wiped off to allow substantial removal of saidsubstance from the skin surface. The substance of high absorption,however, is substantially not removed from hair duct openings. A sourceof electromagnetic energy is then allowed to irradiate and subsequentlyheat and cause expansion to the substance of high absorption at thefollicular duct openings. Such an expansion allow drainage and cleaningof the duct openings.

[0032] An alternative embodiment contemplates a method and apparatus forboth the treatment and prevention of occurrence of acne and is disclosedbelow.

[0033] The method relies on the creation of differential openings in theskin, in particular, differential openings in the human skin.

[0034] The phenomena of acne occurs due to improper drainage of the hairfollicle opening. The hair follicle opening is approximately on theorder of from about 50 μm to about 100 μm. The opening of any other poreon the skin is substantially smaller than that. In particular theopening of the sweat pores are less than about 30 μm in diameter.

[0035] The method and apparatus disclosed consists of the followingsteps:

[0036] a) In the event that hair is growing out of the targeted skinarea, the first step is to remove the hair shaft of the follicle area.Such removal can be accomplished, for example, by means of waxdepilation, mechanical removal or chemically removing the hair from theskin.

[0037] b) Applying a substantially reflective coating to the skin. Thereflective coating comprises a suspension of reflective particles, thatare capable of reflecting substantially most of the light impinging onthem and absorbing very little of the impinging electromagneticradiation. For example, metal-based particles could easily reflect 90%of the incident light.

[0038] The reflective particles in the suspension substance should alsobe of a size that is larger than the size of sweat pores in the skin ofthe patient. Preferably, the particles in the reflecting substanceshould be greater than 30 μm. The particles in the suspension particles,however, should be smaller than the size of the hair follicle opening inthe targeted skin area. Preferably, the particles in the reflectingsubstance should be between about 30 micrometer and about 80 micrometer.

[0039] c) Reflecting particles in suspension are rubbed into the skin sothat the reflecting coating is covering the skin and sweat pore (or anyother openings in the skin). Furthermore, the reflecting particles areforced into the hair follicle opening so that they substantially do notcompletely block the hair follicle openings.

[0040] d) Next, an electromagnetic or other energy source capable ofbeing substantially reflected by the high reflective particles in thesuspension is applied to the skin. The applied energy is reflected frommost of the skin surface, but is trapped and propagated down the hairfollicle to

[0041] i) Remove the substance blocking the opening through the processof ablation, thus allowing enhanced pore drainage. Or, alternatively,

[0042] ii) To thermally heat and destroy the blocking substance in theopening of the hair follicle thus allowing enhanced drainage.

[0043] iii) To cause partial or complete destruction of component withinthe hair follicle and the hair follicle itself, thus allowing enhancedpore drainage or elimination of secretion from the treated follicles.

[0044] Since often hair growth is not desired in the areas effected byacne (for example, facial skin) elimination of hair growth mightconstitutes an additional benefit of the hair shaft within the follicle.

[0045] e) An alternative embodiment incorporates the use of highlyprecise interactions such as those generated by very short pulses may beparticularly useful since such interactions are limited in space and mayminimize any collateral damage in the area adjacent to the targetedopening of the hair follicles. In addition, localization of interactionmay be enhanced due to “funneling” of incoming radiation toabove-threshold level due to coating of the walls of the follicularopenings.

[0046] f) In another preferred embodiment, a short pulse of sufficientlyhigh peak power is directed towards a target skin with high absorbingsubstance confined only to the hair follicles opening (for example, byone of the methods described above). Because of the high peak intensityand the localization of energy density in the high absorbing substance,an explosive interaction will be initiated only in the opening of thehair follicle allowing physical and opening of the hair follicleopening, thus allowing enhanced drainage.

[0047]FIG. 1 illustrates the principle of operation of the presentinvention as described by the embodiment involving a substance of highabsorption and high thermal expansion. In this embodiment hair shaftsare, if present, first removed from the surface of the skin to betreated for acne. They may be removed by either mechanical, or chemicalmeans or by waxing.

[0048] As shown in FIG. 1A, the surface of the skin, 100, is firstcovered by a substance containing components characterized by a largeoptical absorption and high thermal expansion 120. These components inthe applied substance may or may not be the same material. The substanceapplied to the skin, 120, may, for example, contain one, two, or moredifferent types of material each serving a different purpose (one mayyield significant thermal expansion while the other may yield asignificant optical absorption).

[0049] The applied substance 120 is then rubbed and forced to penetratethe hair follicle opening 110 on the skin surface. Such a forceful skinpenetration may also be accomplished by using an ultrasound orsupersonic device to force the material farther into the skin pores. Theparticles within the applied substance 120 are designed to be largeenough where they are unable to penetrate the sweat pores 105, but smallenough to allow them to penetrate the hair duct openings.

[0050] As shown in FIG. 1B, the substance applied to the skin is thenscraped off by means of a rigid edge 200 or is simply wiped off the skinsurface as shown in FIG. 1B. This results in a relatively clean surfacewith an accumulation of the substance of high absorption and highexpansion 120 substantially only in the hair ducts.

[0051]FIG. 1C shows a source of electromagnetic radiation 140 which issubstantially not absorbed by the skin but is well absorbed by thesubstance 120. The resulting radiation 140, is applied to the skinresulting in a rapid expansion of the substance of high absorption andhigh expansion 120, in the direction shown by the arrows 180. Thisexpansion will allow opening of the pores and drainage of the pores. Theheat generated thereof, may also allow localized destruction of bacteriaand cleaning and sterilization of infected area. To minimize pain andcontrol the spread of thermal energy a cooling agent 170 (for example, acryogen spray or a cooled air flow) may also be applied a short timeinterval after the radiation is applied. Such localized heating and amore global cooling may enhance the expulsion of infected material outof the treated hair follicle ducts.

[0052] Additional embodiments include:

[0053] A) Applying a substance consisting of a suspension of highthermal conductivity (HTC) to the area to be treated. Forcing saidsubstance into the hair ducts. Forcing the HTC substance down the hairducts, for example, by the use of an ultrasound field. The HTC substanceparticle should be large enough as to not enter sweat pores or any otheropening in the skin other than the hair duct openings (about greaterfrom 40 μm, but smaller than about 80 μm). Superficially wiping off thesurface of the targeted surface but not removing it from the hair ducts.Applying a heat source or a laser to the surface. The skin is aninsulator, so substantially most of the HTC substance will heat up andopen up the pores and allow cleaning of the hair ducts.

[0054] B) Applying a substance of high absorption to the surface of theskin. Forcing said substance down the hair ducts. The particles in saidsubstance are such that they are not capable of penetrating into anyother pores on the skin surface. Wiping the surface off substantiallywithout removing said substance from the hair ducts. Applyingelectomagnetic radiation to the surface of the skin so that light issubstantially absorbed mostly by the substance of high absorption thatis retained in the hair ducts. Applying light to selectively ablate orheat only the region of the opening of the hair ducts to allow drainageand cleaning action of the hair ducts.

[0055] C) Applying a substance of high absorption to the skin andforcing said substance down the hair follicle. Wiping off excesssubstance on surface. Irradiating with a pulse duration such that noheat is transferred to adjacent tissue and rapid heating and expansioninteraction occurs at follicle openings.

[0056] D) Applying a substance of high absorption to the skin andforcing said substance down the hair follicle. Wiping off excesssubstance on surface. Irradiating with a pulse duration such that noheat is transferred to adjacent tissue and rapid heating and expansioninteraction occurs at follicle openings.

[0057] E) Applying a substance of high absorption to the skin andforcing said substance down the hair follicle. Wiping off excesssubstance on surface. Irradiating with a pulse duration such that noheat is transferred to adjacent tissue and rapid heating, expansion andmelting of “absorbing plug” occurs at follicle openings.

[0058] F) Applying a substance of high reflection to the surface of theskin. Removing said substance from around the hair ducts. The particlesin said reflective substance are such that they are not capable ofpenetrating (are too large) into any pores on the skin surface.

[0059] G) Applying a substance of high absorption to the surface,forcing said substance down the hair ducts. Particles in said substanceare such that they are not capable of penetrating into any other poreson the skin surface. Wiping surface off substantially removing saidsubstance from the skin surface but substantially not removing saidsubstance of high absorption from hair duct openings.

What is claimed is:
 1. A method for treating acne and cleaning hairfollicle ducts of unwanted material, the method comprising the steps of:applying to the skin a substance capable of absorbing energy andexpanding under the influence of the absorbed energy thereby opening thehair duct and releasing undesired substances which are trapped withinthe hair ducts; and applying energy to said substance and causing it toexpand thereby enhancing the opening of the hair follicle ducts.
 2. Themethod of claim 1 wherein the substance capable of absorbing energy andexpending is removed from the skin surface except for the hair follicleopenings and ducts and the external influence is an electromagneticenergy source.
 3. The method for treating acne of claim 1, the methodcomprising the steps of: applying to the skin a substance of capable ofexpanding under willfully triggered external influence, coating to askin area being treated with a substance of high reflectance; andapplying energy to the skin area such that the energy is substantiallyreflected by the reflective coating and is substantially propagatedthrough the hair follicles so as to mitigate blockage thereof.
 4. Themethod as recited in claim 2, wherein the step of applying a reflectivecoating comprises applying reflective particles having a size which istoo large to generally fit within sweat pores and which is small enoughto fit within the hair follicle openings.
 5. The method as recited inclaim 3, wherein the step of applying reflective coating comprisesapplying reflective particles having a size between approximately 30 μmand approximately 80 μm.
 6. The method as noted in claim 1, furthercomprising the step of removing hair from the skin area being treated.7. The method of claim 2 wherein the electromagnetic source comprises ashort pulse electromagnetic radiation.
 8. The method of claim 1 furthercomprising the steps of: disposing a thermal conductivity enhancingsubstance within follicles of the skin area being treated; and applyingenergy to the skin area being treated, the energy being substantiallytransmitted by the thermal conductivity enhancing material to a blockageof the follicle so as to mitigate the blockage of the follicle.
 9. Themethod as recited in claim 8, wherein the step of dispersing a thermalconductivity enhancing substance within follicles comprising usingultrasound to cause the thermal conductivity enhancing substance to moveinto the follicles.
 10. The method as recited in claim 1, wherein thestep of applying an external influence comprises applying heat energy.11. The method as recited in claim 1, wherein: the step of applyingexternal influence comprises applying laser energy; and wherein thesubstance capable of absorbing energy and expanding is capable ofabsorbing the applied laser energy, converting it into thermal energyand expanding under this energy influence.
 12. The method as recited inclaim 1, further comprising the step of removing hair from the folliclesprior to application of the energy absorbing substance.
 13. The methodas recited in claim 1, further comprising the steps of removing hairfrom the follicles prior to disposing the electromagnetic radiationabsorption enhancing substance within the follicles but afterapplication of the energy absorbing substance.
 14. The method as recitedin claim 1, further comprising the step of disposing a thermalconductivity enhancing substance within the follicles prior to the stepof applying an energy absorbing substance.
 15. A method for treatingacne, the method comprising the steps of: applying a reflective coatingto a skin area being treated; removing the reflective coating proximatea blocked hair follicle; and applying electromagnetic energy to the skinarea, the electromagnetic energy being substantially reflected by thereflective coating so as to protect tissue and the electromagneticradiation propagating through tissue where the reflective coating hasbeen removed so as to mitigate blockage of a follicle.
 16. The method ofclaim 15 wherein the area where coating proximate to a blocked hairfollicle has been removed is from about 0.1 mm in diameter to about 10mm in diameter.
 17. A method for enhancing skin elasticity the methodcomprising the steps of: applying external stimulus to generate periodicexpansion and contraction of the skin.
 18. The method of claim 17,wherein the external stimuli constitutes applying external heat sourceto generate periodic (in time)expansion and contraction of the skin 19.The method of claim 17, wherein the external stimuli constitutesapplying external heat source to generate periodic expansion followed bythe application of a cooling agent to generate periodic contraction ofthe skin.
 20. The method of claim 17 for maintaining skin elasticity andpreventing skin aging, the method further comprising the steps of: a)applying a substance capable of absorbing electromagnetic radiation to aportion of the targeted skin, b) applying electromagnetic radiation togenerate periodic (in time and space)expansion and contraction of theskin. c) further applying a cooling agent to enhance the skincontraction phase.
 21. The method of claim 20 wherein the absorbingsubstance is applied to the skin in a spatial pattern that enhancescontraction and expansion of the skin.
 22. The method of claim 20wherein the absorbing substance is applied to the skin in a manner thatenhances contraction and expansion of the skin.
 23. The method of claim17 for maintaining skin elasticity and preventing skin aging, the methodcomprising the steps of: a) applying a substance capable of reflectingelectromagnetic radiation to portion of targeted skin, b) applyingelectromagnetic radiation to generate periodic (in time andspace)expansion and contraction of the skin.
 24. The method of claim 17for enhancing skin elasticity, the method comprises generating a ofperiodic absorption and reflection of electromagnetic radiation to thetargeted skin for a limited time duration.
 25. The method of claim 17the method comprising the steps of: a) applying electromagneticradiation capable of penetrating the skin and capable of being absorbedby the elastin to generate periodic (in time and space) contraction ofthe elastin.
 26. The method of claim 17, the method further comprisingthe step of modulating the energy source power in order to generate aperiodic expansion and contraction of the skin.
 27. The method of claim17, the method further comprising the step of modulating the absorptionand reflection pattern on the skin surface in order to generate periodicvolumetric changes in the skin.
 28. The method of claim 17, the methodfurther comprising the steps of modulating a cooling agent actionapplied to the targeted material in order to generate a periodicexpansion and contraction of the skin.
 29. A device for enhancing skinelasticity, the device comprising the steps of: a) dispensing asubstance of high absorption substantially only to the hair follicleopenings, b) generating electromagnetic radiation to which interactswith the substance of high absorbency in the hair follicle openinggenerates a time-periodic expansion and contraction of the skin.